This invention relates to a portable perimeter pressure sealer module for repairing and/or sealing business forms utilizing pressure sensitive adhesive strips.
In commonly assigned, copending patent application Ser. Nos. 07/417,775 filed Oct. 31, 1990, 07/647,984 filed Jan. 30, 1991, 07/656,439) filed Feb. 19, 1991 there are disclosed methods and apparatus for perimeter pressure sealing of business forms which utilize pressure sensitive adhesives about their perimeters (usually in relatively thin strip form) rather than, for example, heat activated adhesives. The methods and apparatus disclosed in those patent applications, while effective for a wide variety of applications, are nevertheless too complex for certain other applications where low cost, portable units are more desirable. These other applications may include repair of individual forms or even original sealing of small numbers of forms.
In commonly assigned copending patent application Ser. No. 07/605,797, filed Oct. 31, 1990, there is disclosed a table-top pressure sealer designed to handle business forms on a manual feed or semi-manual feed basis. As described in that application, first and second feed rollers convey business forms through the sealer and are driven by a single motor-driven gear which meshes with additional gears integrally formed on the rollers. Pressure applying rollers are mounted above and in alignment with the first and second rollers, and are biased by an adjustable spring mechanism which provides the necessary pressure to affect activation of the pressure sensitive adhesive. The spring mechanism is arranged generally vertically so as to create compression forces perpendicular to the rotational axes of the pressure rollers.
It will be appreciated, however, that where peripheral pressure surfaces of cooperating rollers are biased into engagement with their respective rotational axes parallel, there will necessarily be a slight tilting of one or the other of the axes (and hence one or the other of the peripheral pressure surfaces) of the pressure rollers, thereby causing non-uniform application of pressure on the adhesive strip located between two (or more) form parts.
In the present invention, a portable perimeter pressure seal module for repair or low cost sealing of business forms utilizing pressure sensitive adhesive along one or more perimetral edges is provided wherein the mechanism for applying compressive force between cooperating upper and lower pressure sealer wheels is oriented in a direction generally parallel to the rotational axes of the sealer wheels. At the same time, the sealer Wheels are mounted so that when their rotational axes are parallel, there is a slight gap (less than the thickness of the form) between their respective peripheral sealing surfaces.
This arrangement causes the peripheral sealing surface of one sealer wheel in each of a pair of sealer wheels to assume a non-parallel orientation with respect to the peripheral sealing surface of the cooperating sealer wheel prior to the introduction of a form between the wheels. Upon such introduction, however, the upper sealer wheel (in the exemplary embodiment) is resiliently biased to a substantially parallel orientation vis-a-vis the peripheral sealing surface of the cooperating lower sealer wheel. As a result, uniform sealing pressure is applied to the pressure sensitive adhesive strip as the business form passes through the sealer module.
The above described arrangement is made possible through the utilization of a unique frame structure which mounts the sealer wheels as described in greater detail hereinbelow.
In accordance with one exemplary embodiment of the invention, the perimeter pressure sealer module frame assembly includes a front frame and a rear support frame held in spaced parallel relation by a plurality of tie bars. The tie bars extend between lower portions of the front and rear frames to maintain a substantially rigid connection therebetween. The front frame also has an upper portion which is connected to the lower portion by a pair of vertically arranged planar spring hinge inserts extending between the upper and lower portions. At the same time, the upper portion of the front frame is connected to the upper portion of the rear frame by a pair of horizontally arranged springs which permit controlled flexing of the upper portion of the front frame relative to both the lower portion of the front frame and to the rear frame. It will be understood that references herein to "vertical" and/or "horizontal" are merely intended to facilitate an understanding of the exemplary embodiment of the invention in one orientation relative to, for example, a supporting surface such as a table top.
The frame assembly rotatably mounts two pair of cooperating sealer wheels, one pair located downstream from the other pair in a direction of movement of the form through the sealer module. The upper sealer wheels of each pair are mounted to the upper portion of the front frame, while the lower sealer wheels of each pair are mounted to the lower portion of the front frame. It will thus be appreciated that the upper sealer wheels of each pair are movable relative to the respective lower sealer wheels by reason of the flexible mounting arrangement of the upper portion of the front frame.
More specifically, the pair of springs extending horizontally between the upper portion of the front frame and the rear frame exert a force on the upper portion of the front frame in a direction generally parallel to the axes of rotation of the sealer wheels. Because of the flexible connection between the upper and lower portions of the front frame, however, the applied force tends to pivot the upper portion of the front frame and the upper sealer wheels about the vertical spring hinge inserts and away from the rear frame, so that the peripheral sealing surfaces of the upper sealer wheels are biased to a non-parallel orientation with respect to peripheral sealing surfaces of the lower sealer wheels.
When a business form is introduced between the sealer wheel pairs of the module, the upper sealer wheels, along with the upper portion of the front frame, are forced to pivot back toward the rear frame against the biasing force exerted by the horizontal springs extending between the upper portion of the front frame and the rear frame, so that the peripheral sealing surfaces of the upper sealer wheels now extend substantially parallel to the peripheral sealing surfaces of the lower sealer wheels. This insures uniform application of pressure along the pressure sensitive adhesive strip in the business form passing between the sealer wheels.
In this exemplary embodiment, one of the lower sealer wheels is driven directly by a motor and the other of the lower sealer wheels is driven by means of a pair of pulleys mounted on the sealer wheel axes and a belt extending therebetween. It is also a feature of this invention that the pulley for the downstream sealer wheel has a slightly smaller diameter than the pulley for the upstream sealer wheel so that the downstream sealer wheel feeds faster to thereby prevent wrinkling of the form upon hitting the nip of the downstream sealer wheel pair.
In one exemplary embodiment, there may be provided a pair of O-rings, one extending around the upper sealer wheels and the other extending around the lower sealer wheels. These rings, mounted in peripheral grooves adjacent the peripheral pressure surfaces of the sealer wheels, serve to hold the form and carry it from the first to the second of the sealer wheel pairs. This is particularly critical for any business form which is shorter than the spacing between the sealer wheel pairs.
It is another feature of the invention to provide a platform that supports the form and on which the form can rest as it passes between the sealer wheels. When such platform is utilized, the lower of the two above described O-rings may be omitted.
The sealer module can be used as a stand-alone unit for repair sealing or for manually sealing the perimeter adhesive strips of a form. Alternatively, two or more modules can be combined and configured into various styles of low cost perimeter sealers simply by coupling mirrored units with shafts connecting the sealer wheels of laterally spaced units. This arrangement permits laterally spaced adhesive strips of a form to be activated simultaneously. For a typical form, two passes through the device will seal all four edges.
Thus, in accordance with one exemplary embodiment of the invention, there is provided a pressure sealer for activating a pressure sensitive adhesive strip between a pair of form parts comprising a first frame; at least a first pair of cooperating sealer wheels having first and second peripheral sealing surfaces, respectively, the sealer wheels rotatably mounted in the first frame; and means for causing one of the first and second peripheral sealing surfaces to assume a non-parallel orientation with respect to the other of the first and second peripheral sealing surfaces when no form parts are present between the sealer wheels.
The above described arrangement provides a low cost, effective sealer module for specific, non-sophisticated applications in the business form and related industries.
Other objects and advantages of the invention will become apparent from the detailed description which follows.